\input pstricks.tex
\input pst-node.tex
\nopagenumbers
$
\psset{linewidth=0.8pt,labelsep=0.5ex,unit=2em}
\pcline(0,0)(1,2.5)
\Aput{a}
\pcline(1,2.5)(5,2.5)
\pcline(5,2.5)(4,0)
\pcline(4,0)(0,0)
\Aput{b}
\psset{linewidth=0.4pt}
\psarc{<->}(0,0){0.8}{0}{68.2}
\uput{0.3}[34](0,0){\varphi}
\pcline[linestyle=dashed](3,0)(3,2.5)
\Bput{h}
$
\bye
